Every cancer has its individual mutations, and scientists have long harboured hopes of developing treatments that can be tailored specifically for each individual patient. And now early results from a final-stage trial of personalised cancer vaccines has the research world holding its breath.
US pharmaceutical companies Moderna and Merck have been testing a personalised mRNA vaccine on melanoma patients who had had surgery for their skin cancer. This week, the firms announced that, combined with an established immunotherapy drug, the vaccine had significantly increased the length of time the patients remained cancer-free. This is “a major success in a new field of cancer treatment” that has sent both companies’ shares “surging”, said Reuters.
The results mark “a landmark moment” for the treatment of melanoma, one of the deadliest types of skin cancer, said the study’s principal investigator Georgina Long, medical director of the non-profit Melanoma Institute Australia. This is also “a pivotal moment” for cancer research, said Moderna’s chief executive, Stéphane Bancel.
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How does the vaccine work?
It’s made using mRNA technology – as, famously, were some Covid-19 vaccines. But, while the Covid vaccines were created as a standard formulation for everyone, this time it’s created individually for each patient.
To do that, researchers sequence the DNA of each patient’s tumour (by analysing samples after it’s been removed) and identify its unique mutations. They then “encode selected targets into strands of mRNA”, producing a vaccine designed to teach the recipient’s immune system “to recognise and attack any tumour cells that remain”, said The Times. The result is “a personalised anti-cancer jab” specific to the patient’s tumour, said the BBC.
What do we know about the results?
Very little. The phase 3 trial involved 1,137 high-risk patients with melanoma, who were randomly assigned to receive either the vaccine and the immunotherapy drug Keytruda, or just Keytruda, for about a year.
In a similar smaller trial in 2022, Moderna reported that participants who received the vaccine and Keytruda were 44% less likely to develop new tumours or die within three years, compared to those who only received Keytruda.
Moderna has said that these new trial results “demonstrate statistically significant and clinically meaningful improvements” in survival times for the vaccine group, and that there had been “no new safety concerns”. But we don’t know exactly how much the vaccine increased survival times.
The results have not been publicly released or peer-reviewed. More findings from the trial will be presented at a medical conference in October.
What could this mean?
“I think it’s fair to call this a breakthrough,” said Marco Gerlinger of the Barts Cancer Institute. These results have “much wider implications” than just for melanoma treatment, he told The Times. They are “proof of principle that personalised cancer vaccines work”,
The hope is that this personalised vaccine “will work for many other types of cancer”, said New Scientist. Moderna and Merck are already trialling similar personalised mRNA vaccines for types of bladder, kidney and lung cancer. BioNTech, “the other big mRNA company”, is also testing personalised cancer vaccines in human trials. Several of these early-stage trials have produced “promising results”.
If successful, these vaccines could prevent nearly 50,000 deaths in the US alone, Yale University estimated last year. “The positive hit here leads us into truly this next phase in immunotherapy,” Karen Knudsen of the Parker Institute for Cancer Immunotherapy told Reuters. “This is an auspicious start – this is where things begin.”
What are the caveats?
Moderna and Merck have only released an interim analysis, not the full trial data. And experts “emphasise caution” until the dataset has been peer-reviewed, said the BBC.
The announcement gave Moderna’s shares “their biggest one-day jump on record”, said The Times, while Merck also rallied. But market moves are “imperfect indicators of real-world significance”, said the Financial Times. It’s “not quite the surprise clinical breakthrough” that the jump might imply. It’s “a big deal for Moderna” but, without all data, it’s “difficult to assess the magnitude, durability, and commercial relevance of benefit”.
Investors will be watching for the “next important steps”: “detailed clinical results, regulatory progress, and evidence that the technology works across other cancers”, a financial markets analyst told Sky News. Even then, they know that manufacturing personalised vaccines at scale is “expensive and complex”. One Reuters report suggested that each vaccine could cost about £147,000.
